For many years hospitals and other large buildings have handled disposal of refuse and dirty laundry by the use of mobile units such as carts or similar vehicles which are wheeled along corridors and halls, picking up bundles and then transporting them to a disposal area. This problem is present in all inhabited large buildings but is especially important in hospitals where the disposal problem is continuous, requiring a 24 hour a day operation. Also, in hospitals, there is the liability of disease reinfection which puts an added burden on the operating personnel.
A pneumatic system of chutes and mechanical controls was developed by assignors of Eastern Cyclone Industries, and described in U.S. Pat. Nos. 2,556,056, issued June 5, 1951, entitled "Pneumatic Conveyor System"; 3,208,800, issued Sept. 28, 1965, entitled "Pneumatic Conveying System For Bulky Materials"; 3,606,478, issued Sept. 20, 1971, entitled "Trash And Refuse Depository System"; and 3,847,293, issued Nov. 12, 1974, entitled "Pneumatic Trash-Garbage Pickup Device". Such systems are enclosed and electronically controlled. Once trash or linen is placed in the system's air lock depositories, it is isolated and conveyed through ducts to a centralized collection center. The refuse is never touched by human hands after it is sent on its way and soiled linen is not handled until it reaches a laundry room. Such a completely enclosed system guards against the spread of odors, staphylococci and other pathogens into hospital corridors.
The basic operation of the system described herein is powered by a large suction blower which creates a strong air flow in all the ducts and is capable of moving packages, bundles of all sizes, and individual pieces such as nurses uniforms, bed sheets and towels. The trash or linen is placed in a deposit station by a nurse or other attendant and a button is depressed. The package is then on its way at about 60 miles per hour to its final destination. Since the deposit stations are behind a stainless steel door, mounted flush with a corridor wall, the stations do not interfere with other normal traffic in the halls and do not use any of the elevator facilities. The system removes materials to a central point in the building in which it is installed or, if desired, may continue the movement to another building, outside the hospital area.
The results of this operation are many. First, trash and dirty linen are started on their way from a station near the pick-up point. Second, the speed of delivery is great, moving the packages to their destination in a few seconds. Third, the usual avenues of personnel movement; halls, stairways, and elevators are made free of carts and other carriers. Fourth, the cost of operating a hospital or other building complex is reduced. Finally, the air duct system reduces the fire hazzard since the vacuum system acts to put out any fire which may be started in the bundles.
Although such networks represent a great advance in trash and linen convey operations their speed and operating response is limited because of their mechanical controls. One known control system consists of a relay network. However, such system requires complex circuitry and a great deal of wiring, and attendant therewith increased risk of system failure after continued use. In addition, each control system has to be custom wired for each individual application, no two control systems being alike. In order to change the operation or sequence of any of the elements in the network the wires have to be changed in the field by a skilled technician. It can be appreciated that this can add substantially to the cost for a consumer. Also adding to costs is the fact that because of the amount of wiring required, the enclosures for the control panels must be quite large.
Another known control system, although using solid state circuitry, is in essence, merely a shrunken version of the relay system. The system is still custom built in that each printed circuit board used must be particularly designed for each individual application. Should modification or expansion of a system be desired, it would require a new printed circuit board specifically designed for the particular application. A printed circuit board of one system cannot be used in another different system.
It should be noted that because of the particular circuitry used, both the relay system and the known solid state system may practically use only one travel time for the conveying of packages from station to collector. It can be appreciated that this is not an efficient operating mode in that a station close to the collector should not be alloted the same travel time as that for a station disposed a substantial distance from the collector.
Accordingly, it is an object of the subject invention to provide a control system for operating a pneumatic trash and linen network which is substantially universal, the circuitry of the same type being interchangeable between systems, the circuitry further being programmable to meet the specific requirements of each individual application.
It is a further object of the subject invention to provide a control system for operating a pneumatic trash and linen network which is less costly to manufacture and maintain, and is more efficient than existing systems.